Actinoporins are one of the most studied families of α-pore-forming toxins which were first discovered in sea anemones (Actiniaria) but can be found in other cnidarians as well. Monomeric forms of actinoporins are off roughly 20 kDa, most have a high isoelectric point and lack cysteine residues in their amino acid sequences. In cnidarians, actinoporins are involved in defense against predators and aid in prey capture as they are highly lethal to small crustaceans, mollusks, and fishes. Members of the actinoporin family have a highly conserved three-dimensional fold that consists of the central β-sandwich built of two β-sheets of four and five strands, which is flanked by two α-helices, one on each side. Actinoporins bind to sphingomyelin-containing membranes where they oligomerize and form a transmembrane pore where the amphipathic N-terminal α-helix, rearranges into a longer helix that additionally anchors each protomer into the lipid membrane and forms the walls in the finally assembled pore. Bryoporin is an actinoporin from a moss Physcomitrium (Physcomitrella) patens. Like other actinoporins, bryoporin is hemolytically active against red blood cells, and it was shown that its hemolytic activity can be inhibited by incubation with sphingomyelin, indicating its binding specificity for sphingomyelin. Bryoporin was shown before to be upregulated by various abiotic stresses and especially during water stress [1]. In this study, we combined x-ray crystallography to solve the crystal structure of monomeric bryoporin as well as cryo-electron microscopy to visualize the oligomeric pore. Various experiments on model lipid membranes were used to further characterize the membrane-binding and pore-forming activity of bryoporin. Despite mosses and cnidarians not sharing a recent common ancestor, bryoporin is structurally and functionally an actinoporin, however, its biological role remains to be determined.